Action of food dyes on digestive enzymes (I): Effect of Xanthene Days on the Activities of Trypsin and Chymotrypsin

Abstract

Effects of xanthene dyes on the esterase activities of trypsin and chymotrypsin were examined by using synthetic substrates, Nα-benzoyl-L-arginine ethyl ester and Nα-benzoyl-L-tyrosine ethyl ester, respectively. Xanthene dyes strongly inhibited the tryptic and chymotrypsic activities in proportion to the increasing of light intensity. Also, the concentration and time for 50% inhibition by xanthene dyes and treating period were examined. From these results, it was found that the extent of inhibition was in the following order: rose bengale>phloxine>erythrosine>eosine. Km and kcat values were calculated, using Lineweaver-Burk's plot. The results showed that Km values from both enzymes treated with xanthene dyes were smaller as compared with those of treated enzymes, and kcat values were larger. It was assumed that active sites in the molecules of trypsin and chymotrypsin were degraded by the photo-effect or masked with the dyes. © 1977, Japanese Society for Food Hygiene and Safety. All rights reserved.